Huskerfan27

Will straight piping my 4.9 affect power

265258

Straight pipes suck really bad. You don't need to have back pressure, but you do need something to break up the resonant frequency in the your pipes, resonant frequency meaning the sound and or pressure waves. I learned of this while trying to squeeze power out of motorcycles. Watch this you tube video to see how exhaust sound waves work inside the the pipes. I always like to have some type of muffler or resonator on an exhaust system. I just got done building a new exhaust for my 300 straight 6. I went up to a 2 1/2" pipe, with a cherry bomb. The cherry bomb has nothing to break up the resonant frequency, however, my catalytic convertor did. I looked through and it was still in great shape, not plugged at all, so I installed. It's a pretty good one, and will not slow the flow, but it does provide a means to break up the sound waves in the pipe allowing it to flow smoothly. Sound strange putting a cat on it to most I'm sure, but It will run out better. Eventually I will take the time to make a resonator and get rid of the cat, but for now I'm using it. I will probably weld up a box with an obstacle in it to break up the sound waves. Watch the video you will see what I mean. The pressure waves inside the exhaust pipe are turbulent. When you have a pressure wave exiting a cylinder, having too large of a pipe will cause the pressure wave to slow, then when the next pressure wave exits, it will bounce off of the pressure wave in front of it, causing it to bounce back towards the next pressure wave, it's a cycle. If you create an obstacle in front of the first pressure wave, it doesn't necassarily slow the flow, or CFM of the exhaust, but it can help to even out the pressure pulses and sound waves in your exhaust, creating an even flow. Less turbulence will prevent the pressure waves from bouncing back and slowing the flow. There is a lot of math if you want to get crazy with it, but general rule of thumb, is to have an obstacle to break the cycle of resonant frequency, to create an even flow, rather than leaving the pulses to bounce against each other. It might seem backwards, but a straight pipe does nothing to even out the pulses in your exhaust. You will notice power loss especially in mid range to upper range RPM bands.

MidSouthMitch

Jones Exhaust makes X-pipes in different pipe diameters that I'm going to add to mine.

http://www.jonesexhaust.com/products.cfm?ProductTOC=12

I recently purchased a '92 F150 4.9/C6/4wd that a previous owner "Bubba'd" the exhaust system: 2" pipes from the stock dual manifolds into a common 2x 2" inlet/ 2x 2" outlet muffler, then 2" pipes straight out the back- None of this artfully executed. Its not "loud" but the resonance is obnoxious! Under throttle it sounds like an angry duck call! I'm hoping the X-pipe will tone that down a notch.